Quaternary salts of indigos



QUATERVARY SALTS OF INDIGOS David I. Randall, Easton, Pa., assignor toGeneral Aniline & Film Corporation, New York, N. Y., a corporation ofDelaware 5 Claims. (Cl. 260-296) This invention relates to theproduction of quaternary salts of indigos.

indigos have long been known as valuable vat dyes and indigo itself isknown to be the cheapest and largest selling of vat dyes of any class.They are insoluble in aqueous and spirit solutions and, therefore,cannot be applied substantively to fabrics. They derive their dyeingproperties from their capacity of passing into solution as leucocompounds when reduced with alkaline agents. Such alkaline treatmentconverts the insoluble dye to a phenolic form by reduction of one ormore of the keto groups of the indigo molecule which has the followingconfiguration:

N N H H Alkaline solutions of the reduced compounds possess aconsiderable afiinity for cotton fiber and have the property of beingreadily reoxidized on treatment by air with the precipitation of theoriginal dyestuff.

Although this method produces a fast bond between the dye and the fiberdue to the thorough impregnation of the fiber with the leuco or reducedform of the dye and precipitation of the dye on the fiber duringoxidation, it is obviously subject to limitations. Fabrics which areaffected by alkali cannot be easily dyed by this method. Thus, in wooldyeing it is necessary to neutralize the leuco or reduction solution.Some methods for effecting that result have been proposed, but have notbeen successfully employed. A more successful approach has been the useof leuco esters of the indigo dyes. Other problems requiring carefullycontrolled conditions and special equipment and the use of boosters arealso inherent in. the process of dyeing from leuco vats.

it is, therefore, an object of this invention to produce quaternarysalts of indigos.

With these and other objects in mind it has now been discovered thatindigo and its halogen and alkyl derivatives, as represented by thestructural formula:

nited States Patent-O 2,728,774 Patented Dec. 27, 1955 and preferablyH2504, then introducing bis-chloromethyl ether at temperatures of from 0C. to 30 C. for several hours. In the case of indigo,monochloromethylation is eifected at 0 C. in 100% H2504 when the.reaction is run for 2 hours. Dichloromethylation takes place in the caseof the dichloro indigo at room temperature when the reaction is run for7 hours. Increasing the temperature and the duration of the reactiondoes not increase the number of entering chloromethyl groups in eithercase.

The chloromethylated indigos are relatively insoluble, but are convertedto water-soluble quaternary salts by reaction with a quaternizing agent,such as a thiourea compound producing the isothiouronium quaternarysalts of the chloromethylated indigo and a tertiary amine producing theN-methylene quaternary salts of the chloro: methylated indigo. Thereaction is produced by heating the chloromethylated indigo compound ina paste form with the quaternizing agent over a steam bath withadditions of water and frequent stirring for a period of approximately 1hour, and then diluting the reaction mixture with acetone and water,filtering and slurrying or washing with acetone. The reaction proceedsin accordance with one of the following equations:

wherein Ar is the radical of indigo or a halogen indigo and n is one ofthe integers 1 and 2. The thiourea in Equation 1 may be replaced bythiourea derivatives, such as l-allyl thiourea, l-methyl thiourea,l-phenyl thiourea, 1,3-dimethyl thiourea, 1,3-ethylene thiourea,1,1,3-trimethyl thiourea, and l,l,3,3-tetramethyl thiourea. Thetrimethyl amine may be replaced by other tertiary amines, such aspicoline, isoquinoline, quinoline, diethylaminoethyl alcohol,triethylamine, and benzyldimethylamine.

The quaternary salts derived from trimethyl and tetramethyl thiourea arethe more soluble and, to insure sulficient solubility, it is necessarythat the halogen methylated indigo compound contain an average of atleast one halogen methyl group. Prints made from the quaternary salts ofthe chloromethylated indigos exhibit bright shades of from blue to greenwhich possess excellent fastness to chlorine, washing, and light. Thesequaternary salt dyes, being water soluble, may be used to dye paperpulp, cotton, silk, nylon, and wool. They may also be paste printed oncotton, silk, and nylon and developed by vat of acid aging methods wellknown to the'art. The iso thiouronium quaternary salts of the indigosmay be represented by the formula: v

Al CHQSC A NRiRt 7| wherein Ar is the radical of an indigo or halogenindigo compound, R1, R2, R3, and R4 are-members of the group 7consisting of alkyl, alkylene,.aryl, and hydrogen, of which 12' grams ofindigo powder are added slowly to a stirredsolutionof 16.0 cc..of bischloromethyl ether and 8 cc..of 10.0% sulfuric. acid, held at 0 C. by anice andsalt bath.

Ihesolutionis-stirred. for 2 hours at 0 C. and poured over ice Afterstirring briefly, the formed finely dividgdblue solidis; filtered,washed neutral, and dried. Qf-the product is- 14.7 grams. Chlorinecalcul'ated 11.4%. for monochloromethylatiom found 9.0%. Accordingly,the product of this reaction has the formula:

mont- /O O\ N N U H H EXAMPLE 2 Bis-chloromethyl 4,4-dichloro indigo 12grams of 4,4i-dichloro indigo are introduced into a solution of 16.0 cc.of bis-chloromethyl ether in 70 cc.

100%. sulfuric acid at C. The solution is stirred.

for 7 hours at room temperature, poured over ice, stirredbrifiy,.andthe. formed finely divided blue solid filtered, washedneutral, and dried. The chlorine content calculatedis 33.2% forbis=chloromethylation, found 28.2%. Accordingly, the product of thisreaction has the formula:

'Ihapresence.:of;the.two.symmetrical halogen atoms stabilizes:this-indigo compound to substitution reactions, and in: the:chloromethylation. reaction, two chloromethyl groups::may readily :be'introduced without any polymer formation taking place;

EXAMPLE 3 40.. cc;.of water,,7.0 grams of trimethylthiourea, and

120. grams of.thermonochloromethyl.indigo obtained in Example 1.areheated on a steam bathfor. 1 hour. The

isothiouroniurn salt of the monochloromethyl indigo forms rapidly and athick paste is obtained. The product is isolated by dilution withacetone, filtration, trituration of the precipitate several times withacetone, refiltering, and drying. Awater-soluble blue-green salt isobtained which when printed on cotton yields attractive blue shades;considerably greener. than may be obtained from indigo by the -vettingprocesses mentioned above. The isotliiouronium salt producthas thefollowing formula:

EXAMPLE 4 A suspension of 80 cc. .of; water and '20 grams ofmonochloromethyl indigo, obtained 'inaccordance with Example 1, isheated on a steam bath and 25 grams of thiourea are added. After 1 hourheating the reaction is completed and the resulting dark blue paste ispoured into 400 cc. of water, stirred, and filtered; To the filtrate, 1liter of acetone is added to precipitate the isothiouronium salt. It isfiltered and dried, the weight being 20 grams. The solubilityofthis-compound is somewhat less than that of the trimethylisothiouronium salt of Example 3, but its method of application tocotton is the same. It has the following structuralformula:

k 0 0 c1 osonr E N N n n EXAMPLE 5 A solution of 5 liters of pyridinecontaining 500 grams of. the monochloromethyl indigo obtained inaccordance withyExample 1 is warmed at C. for 48 hours. This heatingperiod is sufficient for complete precipitation of the. pyridiniumchloride. By filtering and washing with acetone to remove pyridine, 450grams of a blue watersolublecompound are obtained. Warming with anaqueous base decomposes the compound, leaving a brown precipitate. Theproduct has the following structural formula:

/CH:-CH\ O O HC l l'CHr E CH=C 6 N N H H Quinoline, picoline, and othertertiary amines may be used equally as well as pyridine in this example.

EXAMPLE 6 300 grams of dichloromethyl-4,4-dichloro indigo as produced inExample 2 and 250 grams .of dimethyl thiourea are heated at.90 C. for 1hour on a steam bath. The product.is;isolated bydilution of acetone,filtration, trituration of the: precipitate several times with acetone,refiltering, and drying. 300 grams of a blue dimethyl isothiouroniumsalt of the dichloromethyl-4,4'-dichloro indigo are obtained.The'product is water soluble and may be printed on cotton goods by theusual methods to form bright blue shades of good light and wash fastnessand fastnessto chlorine. The product has the following structuralformula:

S-bromoindigo, 7,7-dimethylindigo, S,S-dichloro-7,7- dimethylindigo andthe like may be chlorornethylated as in Examples 1 and 2 and theresultant compounds con verted to water-soluble quaternary salts bytreatment with an appropriate thiourea (as in Examples 3 and 4) or atertiary amine (as in Examples 5 and 6).

This application isa division of my application Serial No. 210,428,filed on February 10, 1951', now Patent No.

I claim: 1. A watersoluble compound of the formula:

wherein X is'a member of the group consisting of hydrogen and halogenand wherein X represents a member selected from the class consisting ofhydrogen and an onium radical selected from the group consisting ofisothiouronium and quaternary ammonium salts of negative ionscharacterized by the formula selected from the class consisting of thefollowing formulae:

wherein A- represents an anion selected from the class consisting ofchlorine, bromine, and sulfate, R1, R2, R3. and R4 are selected from theclass consisting of hydrogen, lower alkyl, lower alkylene, and phenyl,Q1, Q2 and Q3 represent lower alkyl groups, and Z represents the carbonatoms necessary to complete a six-membered nitrogenous ring systemselected from the class consisting of pyridine, picoline, quinoline, andisoquinoline, said X being hydrogen only when the other X' is the saidonium radical.

2. A water-soluble compound having the following formula:

5 61 oson CHQN H B211} 0 o 61 OSOH HzN N N H H 4. A water-solublecompound having the following formula:

0 o 110 I IOH CH=CH N N g H H 5. A water-soluble compound having thefollowing formula:

H 01 01 H s o 0 /+NCH| 61 oscmcmsc 51 cum on,

H H N N H H References Cited in the file of this patent UNITED STATESPATENTS 2,657,214 Randall Oct. 27, 1953

1. A WATER-SOLUBLE COMPOUND OF THE FORMULA: